Wire twisting machines that use flyer bows are well known in the art and are commonly used to manufacture twisted wire or cable for a wide variety of applications, including those in the telecommunications and power distribution industries. Wire twisting machines are a class of machines for manufacturing wire or cable, are also referred to as winding, stranding, spinning, cabling, bunching, and twinning machines.
Wire twisting machines create twisted wire by feeding one or more wires from a source along the length of a flyer bow, rotating the flyer bow about a rotational axis, and collecting the finished, twisted wire. Typically, two flyer bows are used in a single machine, but more may be used depending on the application. In operation, a flyer bow can rotate at speeds up to 3,500 rpm and tangential speeds of up to 900 km/h. In operation, a flyer bow may fail due to any number of reasons, including wear and tear, product defect, or external factors including fluctuating wire tension, wire breakage, excessively fast start-up or shut-down of the machine, excessive vibration of the machine, improper balancing, foreign objects left inside the machine that collide with the bow, and human error in the set up or operation of the machine. A flyer bow failure often results in wire becoming entangled in the machine, resulting in costly downtime, scrap, repairs to the machine, and failure of other flyer bows in the machine. Downtime on the machine in which the failure has occurred is likely to cause downtime in downstream manufacturing processes, such as further twisting operations and jacketing operations.
A flyer bow is typically a flexible, convex, arcuate member that guides one or more wires along the length of the inside surface of the flyer bow. Existing flyer bows are typically removable from wire twisting machines for service or replacement and are typically secured to wire twisting machines using fasteners. Typically, each end of the flyer bow has holes to accept one or more fasteners, which align with holes in the wheels of the machine. Fasteners are commonly inserted through the holes of the flyer bow and secured to the machine to hold the flyer bow in place. The steps to replace such a flyer bow include: removing all of the fasteners, removing the flyer bow, aligning the holes of a first end of the replacement flyer bow with the holes of a wheel of the machine, inserting fasteners at that first end, and then, simultaneously: flexing and straightening the replacement flyer bow, aligning holes of the flyer bow at its second end with the holes of the machine's other wheel, and inserting the fasteners at that other end.
Typically, flyer bows are attached to the wheels of a machine using clamp blocks actuated by threaded fasteners to secure an end of the flyer bow to a wheel. The steps to replace a flyer bow include loosening or removing the fasteners, removing the flyer bow, aligning a first end of the replacement flyer bow with respect to a first wheel, tightening or replacing the fasteners at that first end, and simultaneously: straightening and flexing the replacement flyer bow, aligning a second end of the replacement flyer bow with respect to a second wheel and tightening or replacing the fasteners at that second end.
A disadvantage of such apparatus is that fasteners such as nuts, bolts and screws are required to secure the flyer bow to the wheel. The replacement of a flyer bow using fasteners is time consuming, because each fastener must be replaced or tightened.
Another disadvantage is that replacement of flyer bows with fasteners is cumbersome. As described above, the flyer bow must be simultaneously straightened, flexed, aligned and fastened. Multiple workers may be needed to replace a flyer bow using fasteners, for a single worker typically lacks the strength, coordination and dexterity needed to perform these steps simultaneously.
A further disadvantage of the apparatus is that in operation, a foreign object such as a stray fastener or fastener tool may be left inside the machine, become dislodged and collide with the flyer bow. This may cause failure or damage to the flyer bow and the machine, and possibly even personal injury or death of a person located close to the machine.
A flyer bow failure in a machine with multiple flyer bows will usually cause the one or more other flyer bows to fail in that machine. Thus the costs of replacement, labour and time associated with the using fasteners in the replacement of a flyer bow and potential risk of injury tend to multiply with the number of flyer bows in a given machine.